A week ago I swapped out a video card in my gaming machine. i5 2500k on an Asus P8P67 mobo. Everything was unplugged and turned off. I did use a vaccum cleaner with a plastic crevice tool to suck some dust out of the case fans and the corners of the case - as far as I know I didn't get anywhere near the mobo or cpu.

After putting in the new vid card the machine won't POST. Fans spin for 1 sec and then everything powers down. My case doesn't have a speaker (Antec 900) so I don't know if there's a beep code being generated.

I disconnected all drives and left only mobo, RAM and cpu. Same behaviour. I tried a different known good power supply. Same issue. I bought a new motherboard (Gigabyte Z77 DH3), carefully removed the cpu and heatsink, reseated it in the new mobo, and tried both power supplies without success. So now I've tried two mobos and two powersupplies. I've tried both motherboards with one stick of RAM and two.

This leaves me with the unlikely options that BOTH RAM sticks are dead or the CPU is. However from what I've read the CPU should be very difficult to damage barring overheating, and I doubt both RAM sticks died simultaneously.

Do I need to buy a new CPU? Should I try the original mobo again? Go buy a case speaker to find out if there are any beep codes being generated? Any other ideas? I am boggled that changing out a video card has killed my PC!

It is unlikely that your ram sticks are putting your motherboard in a state where it cannot power up. It's possible, but unlikely, and you've already tested alternate configs to try and narrow it down.

Are the symptoms exactly the same with both setups, or is there any change between the two motherboards?

Do you have another machine you can plug the new video card into to certify that it is functional? Otherwise it's first on the RMA/return list :/

Trick to try, learned this with a difficult motherboard a while back.

Pull all the cards from the machine. unplug the drives, etc. Leave only cpu and ram. Now, reset the cmos specifically in this configuration using the (probably) external jumper/button (remember to have the mobo unplugged, and not just unpowered, during this phase...)

See if machine will boot now. If so, re-add new gpu and get yourself back in business.

Atomic

(be sure to check those cpu sockets carefully for pins... it wouldnt be your original problem, but beware giving yourself an all-new headache)

(it's important to pull all the cards from the machine so that the pci/pci-e data gets cleared as well)

Yes, my first post maybe wasn't clear - I'm testing the motherboards without a video card now. Motherboard with a CPU, heatsink / fan and RAM - that's it; no drives, no cards. Both motherboards act exactly the same with both power supplies. (1 second spin up then power down) The only common point in testing both is the CPU, which is why I'm thinking it's next to replace, but I just can't understand how the CPU could have possibly failed. When I reseated it I cleaned it carefully with rubbing alcohol and examined the pins and socket very carefully, and I don't see any visible damage, scorch marks, etc. Not to say that I would see everything, but nothing jumps out as a problem.

I haven't yet tried resetting the CMOS, I will try that, although on the second motherboard which came straight out of the box there wouldn't seem to be much point...

Yes, the circumstances/details are not looking good for your cpu, although I too am a little confused as to how you might have slain the beast. But given that it's the only common thread... (question, have you ever plugged the new video card into the new motherboard?), it pretty much _has_ to be the answer, unless you can come up with another commonality.

After that perhaps a cheap cpu replacement is in order which would verify that it's the cpu causing your headache, although it's yet more money out of pocket.

Thinking through the logic on it. With new intel boards, chips, the gpu is connected directly to the cpu via the pci-e lanes these days. When you inserted the new gpu initially... you mentioned being careful in the vacuuming, but did you have everything unplugged etc? (and even so, it could have been static discharge at this point from your hand through the gpu, and into the board/pci-e lanes)... all you need is to have more negative charge than the motherboard, and it will happen, even if nothing is grounded. (which folks, is why those static straps you wear are grounded through a big resistor... the ground is to drain the static so everything has the same charge level as your local ground, and the big resistor is so you don't fry yourself accidentally, since _you are grounded_) )

This sounds just like what I experienced a while back with a machine a day after we had a funky power spike. Same thing, fan would start to spin then power would die. I thought it was the PS, but that turned out not to be the case. I never did figure out exactly what happened.

Well, if it's the CPU, I'll have to buy a new one, although I really really loved my i5 2500k

Once I get the new CPU I'm inclined to test it in the first motherboard to see if the original mobo was ok or not. If it's still good I can return the second one and recoup some of my expenses. I dislike reseating CPU's multiple times, but for $170 I guess it's worth the hassle.

Any recommendations on a worthy successor to a 2500k? I'm not upgrading the rest of the system so I don't need an i7 which will be head and shoulders over everything else in the box, and money is a bit of an issue. I really liked Sandy Bridge... maybe an i3 Ivy Bridge or Haswell?

Thinking through the logic on it. With new intel boards, chips, the gpu is connected directly to the cpu via the pci-e lanes these days. When you inserted the new gpu initially... you mentioned being careful in the vacuuming, but did you have everything unplugged etc? (and even so, it could have been static discharge at this point from your hand through the gpu, and into the board/pci-e lanes)... all you need is to have more negative charge than the motherboard, and it will happen, even if nothing is grounded. (which folks, is why those static straps you wear are grounded through a big resistor... the ground is to drain the static so everything has the same charge level as your local ground, and the big resistor is so you don't fry yourself accidentally, since _you are grounded_) )

Atomic

Ya, I'm quite sure everything was unplugged - I was on the kitchen table (wood) and the power cord from the PS wouldn't even reach the nearest outlet. It must have been some kind of charge from the vacuum.

Bit the bullet and replaced the CPU with a 3570K. I first tried to get it running in my P8P67 Pro, and it booted but it was giving me all kinds of headaches. The DRAM error led lit up, then while trying to troubleshoot that (I know the RAM is fine) on a breadboard, after 4 or 5 successful starts suddenly the CPU error led lit up and the board wouldn't POST again!

At that point I nearly threw everything out the window, but I pulled out the new mobo, mounted the new CPU, and suddenly everything was fine. I'm going to assume there were issues with the BIOS version on the old board with the new CPU. Supposedly the P67 is compatible with the Ivy Bridge CPU but only with a BIOS update - and I had no way to successfully boot up the board to the BIOS in order to get it updated. Rather than jumping through a bunch of hoops I just used the new Gigabyte Z77 board.

So, long story short, I now have what appears to be a dead i5 2500k (although I'm absolutely mystified how, and I'm very suspicious that the chip might still be ok); an apparently functional P67 board that just doesn't work for my new cpu, and a brand new i5 3570K on a Gigabyte Z77 board. I spent $400 I really didn't want to spend, all after trying to swap out a video card. Stupid computers. This is the kind of thing that pushes people to consoles.

I'm pretty annoyed - that 2500K and P67 Pro was an awesome combo. I've had that build running for a long time (2 years?) and it was OC'd to 4.5 ghz without a sweat. I had no intentions of touching that system for at least another couple years. Oh well...

Uggh that sucks... I had an issue a while back on my gaming rig which turned out to be a power supply gone bad, but I thought it was the vid card and replaced it first to no effect, but I allways leave my pc plugged in but the PS switch off when swapping components so it at least has a ground. Never had a CPU getting fried doing that. I have an i5 2500k as well and its an awesome cpu, I run mine at 4.2ghz and the only reason I dont go higher is I dual boot OSX and Win7 and theres something wonky that happens if I go above 4.2 with OSX so....